libmount Python binding

This week I merged Python libmount binding into util-linux. The original prototype was from Ondrej Oprala (Thanks!).

The binding provides the same functionality as libmount in C -- for now supported objects are:

• Fs - filesystem description
• Table - tab files parser and container for filesystems
• Context - high-level API to mount/umount.   

Examples:

$ python                                                        
>>> import libmount                                             
>>> tb = libmount.Table('/proc/self/mountinfo')                 
>>> fs = tb.find_target('/home/kzak')                           
>>> print fs.source                                             
/dev/mapper/luks-10d813de-fa82-4f67-a86c-23d5d0e7c30e  

# python                                                        
>>> import libmount                                             
>>> cx = libmount.Context()                                     
>>> cx.target = '/mnt/backup'                                   
>>> cx.mount()                                                   
>>> fs = cx.mtab.find_target('/mnt/backup')                     
>>> print fs.fstype
nfs4

# python -c "import libmount; libmount.Context(target='/mnt/backup').umount()"

The side effect of the work on the Python binding is that libmount uses reference counting for libmnt_{fs,table,cache} objects now. So we're ready for more complicated scenarios.

.. and --without-python if you don't like it ;-)